US11119615B2 - Fingerprint sensor and button combinations and methods of making same - Google Patents

Abstract

It will be understood by those skilled in the art that there is disclosed in the present application a biometric sensor that may comprise a plurality of a first type of signal traces formed on a first surface of a first layer of a multi-layer laminate package; at least one trace of a second type, formed on a second surface of the first layer or on a first surface of a second layer of the multi-layer laminate package; and connection vias in at least the first layer electrically connecting the signal traces of the first type or the signal traces of the second type to respective circuitry of the respective first or second type contained in an integrated circuit physically and electrically connected to one of the first layer, the second layer or a third layer of the multi-layer laminate package.

Description

CROSS-REFERENCE

This application is a continuation of copending U.S. patent application Ser. No. 15/489,561, filed on Apr. 17, 2017, which is a continuation of U.S. patent application No. Ser. 14/050,012, filed on Oct. 9, 2013, which claims priority to U.S. Provisional Patent Application No. 61/713,550, filed on Oct. 14, 2012, and U.S. Provisional Patent Application No. 61/754,287, filed on Jan. 18, 2013. All of the foregoing applications are incorporated by reference in their entireties.

BACKGROUND OF THE INVENTION

Biometric sensors and imagers, including, e.g., fingerprint sensors and imagers like those disclosed in the present application are known in the art and are disclosed, e.g., in U.S. Pat. No. 7,099,496 to Benkley, issued Aug. 29, 2006, for SWIPED APERTURE CAPACITIVE FINGERPRINT SENSING SYSTEMS AND METHODS; U.S. Pat. No. 7,463,756 to Benkley, issued Dec. 9, 2009, for FINGER POSITION SENSING METHODS AND APPARATUS; U.S. Pat. No. 8,165,355 to Benkley, issued Apr. 24, 2012, for METHOD AND APPARATUS FOR FINGERPRINT MOTION TRACKING USING AN IN-LINE ARRAY FOR USE IN NAVIGATION APPLICATIONS; U.S. Pat. No. 7,751,601 to Benkley, issued Jul. 6, 2010, for FINGER SENSING ASSEMBLIES AND METHODS OF MAKING; and US Patent Application Publication Nos. US2011/0304001, published Dec. 15, 2011, entitled FINGERPRINT SENSING CIRCUIT; US2012/0189166 published Jul. 26, 2012, entitled USER INPUT UTILIZING DUAL LINE SCANNER APPARATUS AND METHOD; and US2012/0256280, published Oct. 11, 2012, entitled PACKAGING FOR FINGERPRINT SENSOR AND METHOD OF MANUFACTURE. As these types of sensors are used in more and more forms of portable/mobile computing/communications devices, such as cell phones, Blackberries, and other forms of personal digital assistants (“PDAS”), electronic pads, tablets, notebooks, etc. (collectively “portable computing devices”), there is a need for both a more miniaturized, especially thinner, and durable sensor device.

Such sensors have also been incorporated into and/or integrated with such user portable/mobile computing/communications devices and, in particular can be integrated with a button on such a user device that performs some other function for the user device other than gathering biometric data for user authentication or other uses. It has become important, therefore, for such sensors, when so incorporated/integrated, to be durable and able to survive somewhat extreme conditions of stress, as an example, during failure testing, such as drop testing, and then later while in actual use. The present application addresses various aspects of this need in the art.

Since its inception, fingerprint sensing technology has revolutionized biometric identification and authentication processes. In most cases, a single fingerprint can be used to uniquely identify an individual in a manner that cannot be easily replicated or imitated. The ability to capture and store fingerprint image data in a digital file of minimal size has yielded immense benefits in fields such as law enforcement, forensics, and information security.

However, the widespread adoption of fingerprint sensing technology in a broad range of applications has faced a number of obstacles. Among these obstacles is the need for a separate and distinct apparatus for capturing a fingerprint image. Additionally, such components are often impractical for use in systems that are designed to be of minimal size or weight. As handheld devices begin to take on a greater range of functionality and more widespread use, engineers and designers of such devices are constantly seeking ways to maximize sophistication and ease of use while minimizing size and cost. Typically, such devices only incorporate input/output components that are deemed to be essential to core functionality, e.g., a screen, and a limited set of buttons.

For these reasons, fingerprint-based authentication techniques have not replaced username and password authentication in the most common information security applications such as email, online banking, and social networking. Paradoxically, the growing amount of sensitive information Internet users are entrusting to remote computer systems has intensified the need for authentication procedures more reliable than password-based techniques.

An electronic device having a button interface with built-in fingerprint sensing capability would thus lead to increased adoption of fingerprint-based authentication. As will be seen, the present disclosure provides such a system that overcomes obstacles associated with incorporating a fingerprint sensor into an electronic device button interface.

SUMMARY

It will be understood by those skilled in the art that there is disclosed in the present application a biometric sensor that may comprise a plurality of a first type of signal traces formed on a first surface of a first layer of a multi-layer laminate package; at least one trace of a second type, formed on a second surface of the first layer or on a first surface of a second layer of the multi-layer laminate package; and connection vias in at least the first layer electrically connecting the signal traces of the first type or the signal traces of the second type to respective circuitry of the respective first or second type contained in an integrated circuit physically and electrically connected to one of the first layer, the second layer or a third layer of the multi-layer laminate package. The first type of signal trace may comprise drive signal traces and the second type of traces may comprise at least one receive signal trace or the first type of traces may receive signal traces and the second type of traces comprising at least one drive signal trace. The at least one trace of the second type may comprise one trace of the second type and the sensor may comprise a one dimensional linear array capacitive gap biometric sensor. The at least one trace of the second type may comprise a plurality of traces of the second type and the sensor may comprise a two dimensional grid array capacitive gap biometric sensor.

The first layer may comprise a circuit board layer and the second layer may comprise a core layer attached to one side of the circuit board layer. A third layer comprising a circuit board layer may be attached to another side of the core layer. The biometric sensor may be encapsulated on all sides except for a top finger sensing side and may be attached to a substrate. The biometric sensor may be encapsulated on all sides. The biometric sensor may be encapsulated by moldable plastic material formed around the package by a molding process, which also may form an encapsulation molded with rounded edges and corners. The biometric sensor may comprise a biometric sensor mounted on a portable electronic device, and may also cooperate mechanically with elements of a switch, e.g., within the housing of the portable computing device, to operate the switch, i.e., act as a switch operating button.

A user interface, e.g., a button, suitable for incorporation into an electronic device, such as a laptop, tablet, or smart phone or other portable computing devices is disclosed, as well as methods of use and methods of manufacture. The interface can have a housing with a small profile with a thickness less than or equal to 3 mm, an upper layer which fits within a user device housing and sits atop one or more sets of sensor traces in communication with a chip external to the interface via a flexible circuit.

An aspect of the disclosure is directed to an electronic device user interface. Suitable electronic device user interfaces can comprise: a housing having side walls defining an open upper end and a lower surface; a biometric sensor capable of sensing a target biometric parameter having a sensor interface with a sensing side wherein the sensor interface is capable of positioning within the open upper end of the housing; a protective coating on the sensing side of the sensor interface; and an integrated circuit, external to the housing, in communication with the biometric sensor. In some aspects, the protective coating extends over or through one or more side walls of the housing.

Additionally, the biometric sensor further can comprise a flexible circuit substrate and at least one conductive trace connecting the biometric sensor to the integrated circuit. The conductive traces of the flexible circuit substrate can also be positionable on at least one of a side of the flexible circuit substrate facing towards an exterior of the housing and a side of the flexible circuit substrate facing towards an interior of the housing. In some configurations, the device can further comprise one or more of each of: a potting material positionable between the lower surface of the housing and the protective coating; a bezel extending from the side walls of the housing above the bottom of the protective covering; and a removable bottom plate that can attach to the housing to support the biometric sensor. In some configurations, the flexible circuit can wrap around the removable bottom plate. Additionally, an adhesive potting material can be provided between the bottom plate and the protective coating. In still other aspects, the biometric sensor can be capable of capturing a fingerprint from a finger of a user.

Additional aspects of the disclosure are directed to a method of fabricating an electronic device user interface. The method can comprise: providing a biometric sensor having a sensor interface with a sensing side and one or more conductive traces thereon in communication with a flexible circuit; placing a protective coating on the sensing side of the biometric sensor; inserting the biometric sensor into a housing; and providing an integrated circuit external to the housing in communication with the biometric sensor. An additional step can include: forming the protective coating over one or more side walls of the housing. The biometric sensor can be comprised of a flexible circuit having a flexible substrate, wherein the method further comprises the step of: forming at least one conductive trace connecting the biometric sensor to the integrated circuit.

Yet another step can include forming the one or more conductive traces of the flexible circuit on at least one of a side of the flexible substrate adjacent a finger of a user and a side of the flexible substrate facing away from the finger. Still other steps can include one or more of each of: providing an adhesive between the bottom portion of the housing and the protective coating; forming a bezel over at least the edges of the protective covering; providing a bottom plate that attaches to the housing to enclose the biometric sensor; forming the flexible circuit around the bottom plate; and providing an adhesive between the bottom plate and the protective coating.

Still another aspect of the disclosure is directed to a method of using an electronic device user interface. The method can comprise: providing a housing having side walls defining an open upper end and a lower surface, a biometric sensor capable of sensing a target biometric parameter having a sensor interface with a sensing side wherein the sensor interface is capable of positioning within the open upper end of the housing, a protective coating on the sensing side of the sensor interface, and an integrated circuit, external to the housing, in communication with the biometric sensor; and capturing a fingerprint from a finger of a user when the finger is applied to the biometric sensor.

INCORPORATION BY REFERENCE

All publications, patents, and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the disclosed subject matter are set forth with particularity in the appended claims. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which principles of the disclosed subject matter are utilized, and from which they can be illustrated and used, wherein in the accompanying drawings of which:

FIG. 1 shows partly schematically an internal portion of a two dimensional (“2D”) fingerprint sensor array package/housing according to aspects of embodiments of the disclosed subject matter;

FIG. 2 shows partly schematically a cross-sectional view generally along the line2-2 inFIG. 1;

FIG. 3 shows a more detailed version of a portion of the cross-sectional view ofFIG. 2;

FIG. 4 shows top plan view of a sensor encapsulation assembly according to aspects of embodiments of the disclosed subject matter;

FIG. 5 shows a cross-sectional view of a sensor button switch assembly for a mobile communication device, according to aspects of embodiments of the disclosed subject matter;

FIG. 6 shows a perspective view of a version of the sensor encapsulation assembly, according to aspects of embodiments of the disclosed subject matter;

FIG. 7 shows a more detailed view of a portion ofFIG. 6;

FIG. 8 shows a cross sectional view of an example of a transition from a sensor laminated package to a molded encapsulation, according to aspects of embodiments of the disclosed subject matter;

FIG. 9 shows a cross-sectional view of a portion ofFIG. 5;

FIGS. 10A-C show a cross-sectional view of an embodiment of a button having a fingerprint sensor incorporated therein;

FIGS. 11A-C show a cross-sectional view of another embodiment of a button having a fingerprint sensor incorporated therein;

FIG. 12 is a perspective view of a housing with a fingerprint sensor positioned therein;

FIGS. 13A-B illustrate fingerprint sensors suitable for use with the button interfaces disclosed herein; and

FIG. 14 is an illustration of a button having a fingerprint sensor incorporated therein.

DETAILED DESCRIPTION

According to aspects of embodiments of the disclosed subject matter a sensor support housing/package10, as illustrated schematically inFIG. 1, is disclosed. The sensor10 may be a biometric sensor, e.g., a fingerprint sensor having a plurality of pixel locations formed in either a linear one dimensional (“1D”) array or a two dimensional grid (“2D”) array, such as is shown schematically inFIG. 1. As shown by way of example inFIG. 1, the 2D sensor array10 may form agrid20, having transmit/drive signalvertical traces30 and generally perpendicular horizontal receiver signal traces32. The sensor10 can also be seen to include a transmit/drive signal viasection40 to the top of the schematic illustration inFIG. 1, including transmit/drive signal vias44 and a receiver signal via section42 to the left side of the illustration inFIG. 1, including receiver/response signal vias46. It will be understood by those skilled in the art that the schematic view ofFIG. 1 is not to scale and also does not show all of thevertical traces30 or horizontal traces32. It will be understood that usually each of thevias44 is electrically connected to avertical trace30 and each of thevias46 is connected to ahorizontal trace32, so that there are in reality manymore traces30,32 than illustrated inFIG. 1.

Assuming that the horizontal traces32 are in the direction of the width of the finger being sensed, thegrid20 would normally be about 12 mm in that direction and would have around 200 traces32. Ordinarily, for a placement type 2D sensor array10, the perpendicularvertical traces30, aligned in the direction of the length of the finger, would be of the same pitch, but would be more in number, e.g., 600, though schematically inFIG. 1 thegrid20 is shown to be square. It will also be understood that thegrid20 could be of 200horizontal traces32 across the width of the finger and the vertical traces could be less than 200, e.g., a sufficient number to make the grid20 a 12 mm×4 mm grid array, by way of example, such as for a swipe sensor where the sensor captures so called frames of, e.g., from 66 horizontal traces, forming scanned frames that can be reconstructed to form the entire fingerprint image, as is well understood in the art. It will also be understood that the disclosed subject matter could support the packaging of a linear one dimensional capacitive gap array, where there are manyvertical traces30 but only onehorizontal trace32, usually but not exclusively co-planer with thevertical traces30, and acting as a transmitter plate to the manyperpendicular receiver plates30 or a receiver plate to the manyperpendicular transmitter plates30 facing the single plate across a gap, e.g., forming a one dimensional linear capacitive gap array. It will also be understood that, as elsewhere discussed in the present application there is generally at least one layer between thehorizontal traces32 and thevertical traces30, in a 2D grid array, which layer(s) is not shown inFIG. 1.

Turning now toFIGS. 2 and 3, there is shown partly schematically a first cross-sectional view and an enlargement of that view, generally along the line2-2 inFIG. 1.FIG. 2 shows in cross-section view a sensor support housing/package100, having acore layer102, having a thickness of about 100μ, ±20μ, an upper micro-printed circuit board (“PCB”)laminate layer104, having a thickness of about 75μ, ±10μ and a lowermicro-PCB laminate layer106, having a thickness of about 75μ, ±10μ, on either side of thecore layer102. A transparentprotective glass layer120, having a thickness of about 10μ, ±5μ, and an opaque ink rigidprotective layer122, having a thickness of about 15μ, ±5μ along with an uppersolder mask layer130, having a thickness of about 25μ, ±8μ are arranged above the uppermicro-PCB laminate layer104. A lowersolder mask layer132, having a thickness of about 25μ, ±8μ lies below the lowermicro-PCB laminate layer106. These layers form a composite laminate forming a pin grid array (“PGA”)package100, to which an integrated circuit die140, having a thickness of about 150μ, ±12μ, may be attached using an underfill layer150, having a thickness of about 70μ, ±10μ.

Upper micro-PCB laminatetop traces170, may be formed partly in the uppermicro-PCB laminate layer104 and partly in the uppersolder mask layer130. Upper micro-PCB laminate layer bottom traces172, may be formed, partly in the uppermicro-PCB laminate layer104 and partly in thecore layer102. Lower micro-PCB laminate layer top traces174, may be formed partly in the lowermicro-PCB laminate layer106 and partly in thecore layer102. Lower micro-PCB laminate bottom traces176, may be formed partly in the lowermicro-PCB laminate layer106 and partly in the lowersolder mask layer132.

Dieconnective pads190 may be formed on the back side of the integrated circuit die140, and have attached to each of them a dieconnective stud192, as can be seen in more detail, e.g., inFIG. 3, which may be formed on thedie140, e.g., through openings in a mask layer on the back side of thedie140, which may later be removed. Thestuds192 may then be surrounded in theunder fill layer150 and serve to electrically connect a respectivedie connective pad190 to a respective dieconnective stud192, which in turn connects through anopening134 in the lowersolder mask layer132 to a respective lower micro-PCB laminatelayer bottom trace176, e.g., through abump194 that may be grown on therespective stud192 and formed, e.g., of solder.

Core layer102vias180, e.g., connecting a respective upper micro-PCB laminatebottom trace172 to a respective lower micro-PCB laminatetop trace174 may be formed through thecore layer102, e.g., by laser drilling. Upper micro-PCBlaminate layer vias182, e.g., connecting an upper micro-PCB laminate layertop trace170 to a respective upper micro-PCB laminatebottom trace172, may similarly be formed through the uppermicro-PCB laminate layer104. Lower micro-PCBlaminate layer vias184, e.g., connecting a lower micro-PCB laminatetop trace174 to a respective lower micro-PCB laminatelayer bottom trace176, may similarly be formed through the lowermicro-PCB layer106.

Thedie contact plates190, grown on the wafer substrate forming thedie140, may be made of any suitable conductive material, such as aluminum (“Al”), copper (“Cu”) or gold (“Au”), while thecontact studs192 may also be made from a suitable conductive material, e.g., Cu. The contact bumps194 may be made, e.g., of solder and grown on the top of the contact posts192, after they are formed or while the masking material still covers the back side of thedie140 and may extend throughopenings178 formed in the lowersolder mask layer132.

Ball grid array (“BGA”)solder balls200 may extend throughopenings178 in the lowersolder mask layer132 and make electrical contact with lower micro-PCB laminate layer bottom traces176, e.g., to connect thepackage100 to other electrical components of the sensor/imager10, e.g., through traces on a flexible or rigid substrate, e.g.,210, as shown inFIGS. 5 and 9, on which the package/housing100 is mounted.

Turning now toFIG. 5 there is shown, by way of example, asensor encapsulation assembly202. Aflex substrate210, as illustrated inFIG. 5, can be made from a suitable flexible and dielectric material, such as a polyimide film, like Kapton®. The top plan view ofFIG. 4 showsencapsulation material220 encapsulating the package/housing100, as is shown in more detail in cross section inFIGS. 5 and 9, with theencapsulation material220, such as Mold Compound or any number of well known molding compounds, surrounding the package/housing100, and filling in around theBGA solder balls200, which may, e.g., make electrical contact to a trace(s)208 on theflex material210.

Turning now toFIG. 5, there in shown in cross section an example of an embodiment of a mobile device biometric sensor and switchcombination300. The mobile device biometric sensor and switchcombination300 fits within anopening304 in amobile device housing302, such that theupper sensor surface222, formed by theencapsulation material220 of the housing is generally flush with the outer surface of themobile device housing302. The encapsulated sensor package/housing100 may be mounted on aflexible substrate210, as shown inFIG. 9 that may be attached to a mobile device waterproofrubber seal member310, e.g., with awaterproof tape320. The sensor device package/housing may be entirely encased in the encasing material as illustrated inFIG. 9, or, as shown inFIGS. 5 and 7 thetransparent glass layer120 and overlying hardopaque coating layer122 may be exposed through anopening230 in the encapsulatingmaterial220 to facilitate fingerprint sensing. A molded frame/spacer240, which may be made of the same material as the encapsulatingmaterial220, or, as shown inFIGS. 6-8, may be molded in the encapsulation process. The spacer/frame240 may have aflange280, and may serve to hold the encapsulated package/housing100 on theopening302.FIG. 8 shows a cross-sectional view of a portion of an exemplary package/housing100 within, e.g., a sensor encapsulation assembly, surrounded byencapsulation material220 and covered by a relatively thin layer ofrigid material222, applied as an ink originally and allowed to cure.

The mounting of the package/housing100 to theflex strip210 may give the entire assembly enough flexibility such that, when a finger or other object is pressed against the top of the housing,package100 can move enough to operate an underlying mechanical switch, such as adome switch330, which may include a depression member322 and adeformable contact332. Theswitch330 may be connected to circuitry (not shown) on acircuit board350 within the body of the mobile device. A toggling twoposition element332 may form the other contact of theswitch330, such that when the depression member322 is moved into the two position element it “clicks” to a non-contacting dome position and theswitch330 is open when the pressure on the package/housing is removed. When the depressing element is moved back into contact with the twoposition element332, it is “clicked” back to the contacting position and theswitch330 remains closed when the pressure is removed from the package/housing100. A pair ofstops352 engaging thecircuit board350 can insure the flex material does not bend to severely, thus damaging the relatively rigid package/housing100. Aninterposer plate360, attached to the bottom of theflexible strip210, can serve to move the depression member322, when downward pressure is put on the housing/package100.

Thespacer240 may be formed with arounded edge250, to protect the finger of the user. As shown in more detail, inFIGS. 6-8, instead of aseparate spacer240, the encapsulation material may be initially molded around the package/housing100 to form, e.g., aslanted side wall252,rounded corners260 the roundedtop circumference250 of the molded encapsulation, and theflange280. In a variation of the process ofFIG. 4, the moldedencapsulation material220 may be formed over apackage housing100 attacked to traces on theflexible material substrate210 formed to have atrace extension284, which may serve to electrically connect the sensor10 andIC140 to other components of the system.

It will be understood by those skilled in the art that according to aspects of embodiments of the disclosed subject matter, the disclosed multi-layer laminate substrate technology has been employed to create a finger print sensor with a very durable package/housing construction, for biometrically authenticating a user of the mobile device and also suitable for use as part of a mobile device mechanical switch, e.g., for turning the mobile device on and off. The sensor may be formed of a 1D or 2D grid array of various shapes and sizes, with one dimension typically at least as wide as normal human finger. The grid can be formed, as an example, by traces forming conducting leads on opposing sides of a top layer in a laminate of layers on opposing sides of a relatively rigid and strong, e.g., reinforced core layer. Electrical drive circuitry may be connected to the traces on one side of the laminate layer and pick-up/response circuitry may be connected to the traces on the opposing side of the upper laminate layer, with the transmit drive traces typically formed closer to the sensing surface of the sensor, i.e., the top surface of the upper laminate layer.

This top surface (top meaning surface closest to the finger during finger print acquisition), as noted, is usually configured as the transmitter traces and the other metal traces on the reverse side of the layer (farther away from the finger), layer is usually configured as the receiver. response signal traces. As is well known in the art, the traces formed in a 1D or 2D array constitute pixel locations where the presence of the finger creates variations in the receive signal response to the transmitted signal, mostly due to variations in the capacitive coupling of the two through the finger near the top of the sensor10 due to capacitive differences between the presence of a fingerprint valley or ridge in the vicinity of the given pixel location. These variations are detected to generate an finger print image either partly or wholly within the integrated circuit, which can also create the drive signals and time their application to drive signal traces in the grid10.

It will also be understood that the height of the package/housing can vary based on the BGA size, e.g., in order to conform to differing height requirements. Package/housing size can, e.g., correspond to sensing linear array or grid array area, e.g., about 122 mm across in the direction of the width of the finger and the same or more in the direction of the length of the finger. The package body can, e.g., be square, e.g., in embodiments designed for housing the sensor on the top of or embedded within the housing as required to create a round button. The package may have some or all sides formed with a bevel cut package edge, e.g., down to about a 100μ depth, which may, e.g., be formed in a two pass singulation of individual packages/housings from a plurality of packages/housings formed in one operation as discussed elsewhere in the present application.

A PCB or flex interposer may be required to make a housing in which the package/housing is part of actuating a mechanical switch button. Buttons may be manufactured, e.g., by placing a flex strip(s) in a molding jig. The button housing may, e.g., be molded around the biometric sensor formed within the multilayer flip chip housing/package, e.g., with mold compound surrounding the flip chip placed on the flex strip, e.g., in a row of chips format. The flex strip may form a substrate having, e.g., a thickness of around 80μ-120μ. The top portion of the mold material may have, e.g., a thickness of around 50μ and a bottom mold thickness of around 1 mm.

According to aspects of embodiments of the disclosed subject matter, a single sided molded package/housing may be created, e.g., having a base substrate, which may be flexible, or rigid, e.g., a PCB or micro-laminated layer PCB, as discussed elsewhere in the present application, by way of illustration, by the mounting of a flip chip laminate package, described in the present application, to the substrate. The assembly, substrate plus flip chip laminate package, can then be place entirely of mostly within an encapsulation material that may then be molded into a desired size and shape, e.g., by the use of moldable encapsulation material, such as well known molding compounds, plastics, resins, etc. The molding material may be used to fill under the flip chip package and/or around the perimeter and/or on the surface of the package to form a molded button. Such a molded button may be utilized solely with the biometric sensor element to sense finger presence and/or surface movement, and, in response, act as a button, or may be combined with an interposer, such as made from a rigid material, like a PCB, or flexible, such as a flex substrate, e.g., to interact with an adjacent mechanical switch when the biometric, i.e., the finger presses down on the sensor area and thus on the entire package/housing.

The substrate/interposer with a flip chip package attached, and encapsulated by use of injection/transfer/compression molding, or the like, may include on the sensing side an encapsulation thickness that is relatively thin, or even non-existent and selected and adjusted to establish a desired sensing distance from the surface of the actual sensing traces in the flip chip package. Sensing distance can be important to accurate data capture. As one option according to aspects of embodiments of the disclosed subject matter, the sensing side of the package can be encapsulated to protect the sensing area from surface, impact, or moisture damage. This can be done, by way of example, in a single molding step, by using materials with filler sizes appropriate for a top minimum thickness. In an example the minimum thickness over the flip chip package can be, e.g., 30-50μ. This thin layer of material would require the use of a fine filler, e.g. one with filler sizes of 15μ or smaller in the molding compound.

In another example, the assembly can also be encapsulated on all sides with the exception of the upper sensor surface. In such a case, e.g., where the sensor surface is not encapsulated, it can be protected by applying protective coating, e.g., as noted elsewhere, a spray ink coating that hardens as it is cured, and/or a glass or other transparent plastic coating, of, e.g., by a second molding step. The protective coating/coatings to the surface of an exposed flip chip laminate substrate and/or encapsulating area is contemplated.

In a third option another variant may be to add a protective coating/coatings to the surface of the flip chip package prior to assembly on the button substrate and further encapsulation. Such an encapsulation molding process can allow for a wide variety of customization of button sizes and shapes with a single flip chip package/housing by changing of the mold size and shape. Such encapsulation molding processing and materials can also allow radius corners and edges that can not be as easily achieved with standard laminate package technologies.

According to aspects of embodiments of the disclosed subject matter a low cost customizable finger print sensor button, e.g., for the mobile communication device market can be produced. The package/housing body may be, e.g., 10.5 mm×4.0 mm. The package housing may be mounted on a flexible substrate and with supporting components elsewhere on the substrate or on a rigid PCB or a mobile phone board. It is also possible for the flip chip package housing to be mounted to a motherboard with the specified other components also so mounted.

It will be understood by those skilled in the art that there is disclosed in the present application a biometric sensor that may comprise a plurality of a first type of signal traces formed on a first surface of a first layer of a multi-layer laminate package; at least one trace of a second type, formed on a second surface of the first layer or on a first surface of a second layer of the multi-layer laminate package; and connection vias in at least the first layer electrically connecting the signal traces of the first type or the signal traces of the second type to respective circuitry of the respective first or second type contained in an integrated circuit physically and electrically connected to one of the first layer, the second layer or a third layer of the multi-layer laminate package. The first type of signal trace may comprise drive signal traces and the second type of traces may comprise at least one receive signal trace or the first type of traces comprising receive signal traces and the second type of traces comprising at least one drive signal trace. The at least one trace of the second type may comprise one trace of the second type and the sensor may comprise a one dimensional linear array capacitive gap biometric sensor. The at least one trace of the second type may comprise a plurality of traces of the second type and the sensor may comprise a two dimensional array capacitive biometric sensor.

The first layer may comprise a circuit board layer and the second layer may comprise a core layer attached to one side of the circuit board layer. A third layer comprising a circuit board layer may be attached to another side of the core layer. The biometric sensor may be encapsulated on all sides except for a top finger sensing side and may be attached to a substrate. The biometric sensor may be encapsulated on all sides. The biometric sensor may be encapsulated by moldable plastic material formed around the package by a molding process, which also may form an encapsulation molded with rounded edges and corners. The biometric sensor may comprise a biometric sensor mounted on a portable electronic device, and may also cooperate mechanically with elements of a switch within the portable computing device to operate the switch.

Turning now toFIG. 10A is a cross-sectional view of an embodiment of abutton1100 having a one dimensional (1D) or two dimensional (2D)biometric sensor1130, such as a chip on flex (COF)fingerprint sensor1130, incorporated therein. Thebutton1100 can have anupper surface1102 and alower surface1104 and may be configurable to provide, for example, a glass or suitable hard coat orfilm top layer1110 having anupper surface1112 and alower surface1114, which can be surrounded by ahousing1120 on two or more sides. In this configuration, the edges of thetop layer1110 can be enclosed by abezel1122, such as a rim that retains thetop layer1110 within thehousing1120. Theupper surface1112, of thetop layer1110 can serve as an interface for a finger during use of the device and capture of biometric information from the user's finger. Thetop layer1110 can be configured to provide protection for thebiometric sensor1130. Thetop layer1110 can be composed of different materials and/or colors which may also provide decorative identification. Additionally, thetop layer1110 can be formed from a hard material providing mechanical protection to the sensor tracer elements formed, e.g., on theflexible circuit substrate1130. The bottom portion of thehousing1120 can also provide mechanical support for thebutton assembly1100.

Thehousing1120 can be formed from, for example, polycarbonate (PC), acrylonitrile-butadiene-stryrene (ABS) or other suitable material, including any thermoplastic characterized by high-impact strength, as well as metals such as aluminum and titanium. Thehousing1120 can be configured to have abase1124, and parallel side walls1126 (in two dimensional cross-section), anaperture1128 can be provided through whichflexible circuit substrate1132 of thesensor1130 passes to connect to theintegrated circuit1134 which can be positioned away from thehousing1120.

Thetop layer1110 can be formed from glass or any other suitable material such as shatter resistant substitutes for glass, including polymethylmethacrylate (PMMA), polyethylene terephthalate (PET), etc. The biometricsensor element substrate1130 can be formed from, for example, from a flexible circuit substrate formed with flex circuit metal tracer elements on top of aflexible film substrate1132 with the metal traces being in electrical communication with anintegrated circuit chip1134. Theintegrated circuit chip1134 need not form part of the stack of materials, and thus, in that configuration, can provide no mechanical functionality to the sensor/finger interface or mechanical operation of thebutton1100. An adhesive orpotting material1140 in the aperture, such as thermo-setting plastic or silicone rubber gel, can be provided that secures and/or stabilizes the positioning of the sensorflexible circuit substrate1130, forming thesensor1130 in a position between abottom portion1124 of thehousing1120 and thetop layer1110 which is engaged by the user during use. The adhesive orpotting material1140 can consist of different regions or layers depending on the assembly method.

Additionally, the adhesive orpotting material1140 may also consist of multiple adhesives or potting materials depending on assembly method and required properties of thebutton1100. Dimensions of the form factor could be less than or equal to 900 mm², less than or equal to 400 mm², less than or equal to 225 mm², less than or equal to 100 mm², in a first two dimensional aspect. In some embodiments the thickness of the form factor is less than or equal to 2 mm or more preferably less than or equal to 1.5 mm. Further embodiments can have the form factor thickness less than or equal to 1 mm.

Thepotting material1140 in the opening can be selected such that it provides mechanical support for thesensor1130. Impact resistance of thebutton1100 can be enhanced by maintaining a high hardness (modulus) throughout and/or thin adhesive thickness. Further the silicon integrated circuit (IC)chip1134 may not be included in this potting area to avoid thermal expansion, humidity expansion and general durability issues that might arise. That is to say, theflexible substrate1138 can be unfolded from under thebutton1100, as illustrated, e.g., inFIG. 14.

As will be appreciated by those skilled in the art, biometric sensors can include, for example, a fingerprint sensor, a velocity sensor, and an integrated circuit which is electrically connected to the fingerprint sensor and the velocity sensor. Biometric sensors can further include sensors adapted and configured to capture one or more parameters of, for example, a fingerprint. Conductive traces (not shown inFIG. 10A) of an image sensor and velocity sensor can be etched or otherwise formed on a side of theflexible circuit substrate1130 facing theupper surface1112 of thebutton1100. Moreover, the traces can be positioned on theflexible substrate1130 such that the traces are up (and thus on anupper surface1136 of thesubstrate1132 proximal to the top layer1110), or the traces are down (and thus on alower surface1138 of the substrate distal the top layer1110). In some configurations, theflex circuit1130 on theflex substrate1132 can be configurable to have functionality (i.e., traces formed) on both the upper surface1336 and thelower surface1138 which enables the width of theflex1130 to be reduced, and also reduces the overall package size. Moreover thebutton1100 can be part of a mechanically functional switch or a mechanically fixed button. Additionally, thebutton1100 can be used for biometric sensing (fingerprint sensing), navigation, or touch sensing.

As will be appreciated in reviewingFIG. 10A, theIC chip1134 need not be positioned within the stack of materials. Where theIC chip1134 is positioned away from the stack of materials forming the button, thebutton1100 can achieve a more compact profile and lower height which makes thebutton1100 more adaptable to be incorporated into an electronic device, such as a smart phone or touch pad. Additionally, the configuration enables the properties (e.g., cover, adhesive material, housing) to be tuned for functionality and durability.

In configurations where the conductive traces are positioned on the top side of theflex1136, a protective coating can be applied to theupper surface1136 of theflex substrate1132 itself, over the image sensor and velocity sensor to provide electrical isolation and mechanical protection of the sensors. Alternatively, conductive traces of an image sensor can be formed on a bottom-side1138 of asubstrate1132, wherein thesubstrate1132 of theflex circuit1130 acts as a protective coating and can be further improved with a hard coating applied to theupper surface1136 of theflex circuit1130 itself.

Further details about fingerprint sensor configurations are contained in, for example, U.S. Pat. No. 7,751,601 to Benkley III for FINGERPRINT SENSING ASSEMBLIES AND METHODS OF MAKING; U.S. Pat. No. 7,099,496 to Benkley III for SWIPED APERTURE CAPACITIVE FINGERPRINT SENSING SYSTEMS AND METHODS; U.S. Pat. No. 7,463,756 to Benkley III for FINGER POSITION SENSING METHODS AND APPARATUS; U.S. Pat. No. 7,460,697 to Erhart et al. for ELECTRONIC FINGERPRINT SENSOR WITH DIFFERENTIAL NOISE CANCELLATION; U.S. Pat. No. 7,146,024 to Benkley III for SWIPED APERTURE CAPACITIVE FINGERPRINT SENSING SYSTEMS AND METHODS; U.S. Pat. No. 6,400,836 to Senior for COMBINED FINGERPRINT ACQUISITION AND CONTROL DEVICE; and U.S. Pat. No. 6,941,001 to Bolle for COMBINED FINGERPRINT ACQUISITION AND CONTROL DEVICE. As will be appreciated by those skilled in the art, the sensor can be a 1D swipe sensor, a 2D touch sensor, a 2D motion sensor, a 2D sensor having two layers of electrodes, a 2D sensor having a single layer of electrodes, a 2D sensor with electrodes on either side of theflex substrate1130 substrate. Moreover, multiple conductor materials can be used to form the sensor, such that different layers are made from different materials to achieve different results and for different reasons.

Thebutton1100 can be configurable such that it has a transparent interface, an opaque top coat, or a mask layer, and can be formed such that the upper surface material is not visually transparent. Additionally, the upper surface can be configurable such that it provides a variety of tactile interfaces, e.g., rough or smooth. An “anti-fingerprint and/or anti-smudge” (“AF”) and/or a hard coating can be applied.

FIG. 10B is a cross-sectional view of another configuration of abutton1100′ having a 1D or 2D biometric sensor, such as a COF fingerprint sensor, incorporated therein. In this embodiment thetop layer1110′, formed from glass or any other suitable material such as shatter resistant substitutes for glass, including polymethylmethacrylate (PMMA), polyethylene terephthalate (PET), extends at least partly on top of some or all of thesides1126′ of thehousing1120′.

FIG. 10C is a cross-sectional view of another configuration of abutton1100″ having a 1D or 2D biometric sensor, such as a COF fingerprint sensor, incorporated therein. In this embodiment thetop layer1110″ is over-molded which extends thetop layer1110″ over and at least partly surrounds at least oneside1126″ of thehousing1120′. Thistop layer1110″ may be formed by over-molding, wet coating or any suitable method.

FIG. 11A is a cross-sectional view of another configuration of abutton2100 having abiometric sensor2130 incorporated therein. Thebutton2100 is configurable to provide, for example, a glass or suitable hard coat orfilm top layer2110 which is surrounded by ahousing2120. Thehousing2120 can be formed from polycarbonate (PC) or other suitable material including but not limited to metals such as aluminum. Thebiometric sensor2130 can be comprised, for example, from aflexible circuit substrate2132 which is in electrical communication with anintegrated circuit2134. This configuration is illustrated to have an adhesive or potting material,2140 which may or may not be necessary depending on the method of manufacture. Theflexible circuit2132 is secured and/or stabilized about an insert plate orsupport2160 that can be fitted within thehousing2120 and, for example, clipped into place. In this configuration theflexible circuit2132 wraps around the insert orplate2160 and then the flex/plate combination can be clipped into thehousing2120. In another example the insert or plate can be clipped into thehousing2120 and then theflex substrate2132 can be wrapped around theplate2160. Additionally, theplate2160 may be placed into position within thehousing2120 using an adhesive, e.g., filling theopening2140, where theflex circuit2130 fits instead of being clipped into place. Adhesive and/or potting materials may also be optionally used. In some configurations, the glass, hard coat or hard film can be bonded directly to the sensorflexible circuit2130flexible substrate2132 or can be so bonded with an adhesive.

FIG. 11B is a cross-sectional view of another embodiment of abutton2100′ having afingerprint sensor2130′ incorporated therein. Thebutton2100′, containing aflexible substrate2132′ with thesensor elements2130′ wrapped around an insert orplate2160′ in electrical communication with thesensor IC2134′ is configurable to provide, for example, atop layer2110′ that extends at least partly on top of some or all of thesides2126′ of thehousing2120′.

FIG. 11C is a cross-sectional view of another embodiment of abutton2100′ having afingerprint sensor2130″ incorporated therein. Thebutton2100″, containing aflexible substrate2132″ with thesensor elements2130″ wrapped around an insert orplate2160″ in electrical communication with thesensor IC2134″ can be configurable to provide, for example, atop layer2110″ that extends over and at least partly surrounds at least one side of the housing, as shown, e.g., at2112″ on either side of theside walls2126″. Thistop layer2110″ may be formed by over-molding, wet coating or any suitable method.

FIG. 12 is a perspective view of abutton3100 having ahousing3120 with afingerprint sensor3130 therein.

FIGS. 13A-B illustratefingerprint sensors130 suitable for use with the button interfaces disclosed herein. Suitable 1D sensors possess from 90 to 300 pixels, or more preferably from 114 to 200 pixels. Suitable 2D sensors possess arrays of pixels in the range of 90 to 300 pixels by 90 to 300 pixels, or more preferentially a range of 114 to 200 pixels by 114 to 200 pixels. A size is from 8 to 30 mm across the broadest length, or more preferably from 6 to 20 mm.FIG. 13A illustrates an example of a 2Dtouch sensor layout4130 on flex;FIG. 13B illustrates an example of a1D sensor layout4130′ on flex.

FIG. 14 is an illustration that shows a top view of abutton5100 having a fingerprint sensor incorporated therein. Thebutton5100 has a pill-shape profile as illustrated, but could be square or circular as required from the implementation. Thebiometric sensor elements5130, either 1D or 2D, can be positioned within a portion of thehousing5120 and positioned to be attached to the top layer5110 (same profile as housing5120). Theflexible substrate5132 can extend from the embedded sensor such that thesubstrate5132 can be wrapped around, for example, a plate (not shown), or otherwise configured to fit within thehousing5120. Theintegrated circuit5134 which controls the operation of the sensor/button5100 is on an opposing end of theflexible substrate5132 and in electrical communication with the sensor elements in the sensor/button5100.

II. Methods of Use

The button interfaces may be housed in a host electronic device and configured to perform both object image capture and at least one of an activation of the host device, an activation of a host device function and an input to the host device. The button interfaces may further comprise the button interfaces configured to allow a user to contact the switch simultaneously with providing object image data through an intersection of the at least one drive line and the at least one pickup line. The object may a finger and the button interfaces configured to sense a fingerprint image. The button interfaces described above can also be used to create a functional button (e.g., on/off), to provide navigation functionality, and/or to provide biometric sensing (such as fingerprint sensing).

III. Methods of Manufacture

In one manufacturing example, the button is manufactured according to the following:

• • Singulate flex by, for example, laser cutting adjoining laminated material.
  • ACF attach connection to flex may occur prior to singulating flex, after singulating flex or after final button assembly.
  • Form housing, for example, using a cast or machine.
  • Provide flex sensor with the ACF board.
  • Flex bonded to housing.
  • Assemble housing if needed.
  • Form top layer either on the flex area only or on the housing only or both the flex and housing. The top layer could be a curable wet coat or cast or hard film bonded with adhesive among other materials.
  • ACF attach connection to flex if not connected previously.

In another manufacturing example, the button is manufactured according to the following:

• • Singulate flex.
  • ACF attach connection to flex may occur prior to singulating flex, after singulating flex or after final button assembly.
  • Form top layer on the flex area. The top layer could be a curable wet coat or cast or hard film bonded with adhesive among other materials. Applying top layer may occur prior to singulating flex.
  • Flex bonded to housing.
  • Housing assembled if needed.
  • ACF attach connection to flex if not connected previously.

In still another manufacturing example, the button is manufactured according to the following:

• • Singulate flex.
  • ACF attach connection to flex may occur prior to singulating flex, after singulating flex or after final button assembly.
  • Top layer bonded to housing. The top layer could be a curable wet coat or cast or hard film bonded with adhesive among other materials.
  • Bond flex to top layer and/or housing.
  • Form support behind flex either by filling using an epoxy and/or bond plate in place.
  • ACF attach connection to flex if not connected previously.

In a fourth manufacturing example, the button is manufactured according to the following:

• • Singulate flex.
  • ACF attach connection to flex may occur prior to singulating flex, after singulating flex or after final button assembly.
  • Attach flex to the bottom plate of the housing.
  • Attach plate/flex combination to the housing.
  • Attach top layer to the housing.
  • Use adhesive or potting material if needed to fill volume.
  • ACF attach connection to flex if not connected previously.

The manufacturing process is configurable to simplify the button manufacturing process using advanced manufacturing techniques while optimizing image capture through the molding compounds and/or layers.

While preferred embodiments of the present invention have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions will now occur to those skilled in the art without departing from the invention. It should be understood that various alternatives to the embodiments of the invention described herein may be employed in practicing the invention. It is intended that the following claims define the scope of the invention and that methods and structures within the scope of these claims and their equivalents be covered thereby.

Claims (4)

What is claimed is:

1. A method for manufacturing a button having a fingerprint sensor incorporated therein, comprising:

singulating a flexible substrate;

attaching an anisotropic conductive film (ACF) to the flexible substrate;

forming a housing;

providing a flexible substrate sensor with an ACF board;

bonding the flexible substrate to the housing;

assembling the housing; and

forming a top layer on the flexible substrate and on the housing, wherein the top layer comprises a curable wet coat, a cast, or a hard film bonded with adhesive;

wherein attaching the ACF to the flexible substrate occurs after singulating the flexible substrate, forming the housing, bonding the flexible substrate to the housing, and forming the top layer.

2. The method according toclaim 1, wherein singulating the flexible substrate comprises laser cutting adjoining laminated material.

3. A method for manufacturing a button having a fingerprint sensor incorporated therein, comprising:

singulating a flexible substrate;

attaching an anisotropic conductive film (ACF) to the flexible substrate;

bonding a top layer to a housing, wherein the top layer comprises a curable wet coat, a cast, or a hard film bonded with adhesive;

bonding the flexible substrate to the housing and/or to the top layer; and

forming support behind the flexible substrate, wherein forming the support behind the flexible substrate comprises filling using an epoxy;

wherein attaching the ACF to the flexible substrate occurs after singulating the flexible substrate, bonding the top layer to the housing, bonding the flexible substrate to the housing and/or to the top layer, and forming the support behind the flexible substrate.

4. A method for manufacturing a button having a fingerprint sensor incorporated therein, comprising:

singulating a flexible substrate;

attaching an anisotropic conductive film (ACF) to the flexible substrate;

attaching the flexible substrate to a bottom plate of a housing;

attaching the attached flexible substrate and bottom plate to the housing;

attaching a top layer to the housing; and

using adhesive or potting material to fill volume;

wherein attaching the ACF to the flexible substrate occurs after singulating the flexible substrate, attaching the flexible substrate to the bottom plate of the housing, attaching the attached flexible substrate and bottom plate to the housing, and attaching the top layer to the housing.

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